Standard (Inches) to metric (mm) conversion table

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harrisonm

harrisonm

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I know most of us are at least somewhat familiar to the standard to metric tool conversions. For example, we all know that a 1/2" wrench is pretty much the same as a 13mm one. Every once in a while, I'll come across a nut or bolt head that is in between two standard sockets. Sometimes I wound up doing a trial and error to find the correct metric conversion. A while back I made up a table of inch to metric conversions in a spreadsheet. I thought I would post this table here. I checked it out very carefully, so I hope there are no errors. I hope it comes in handy for someone.


64th" Decimal" Reduced mm Socket
1 / 64 = .015625 = 1/ 64 = 0.40

2 / 64 = .03125 = 1/ 32 = 0.79

3 / 64 = .046875 = 3 / 64 = 1.19

4 / 64 = .0625 = 1/16 = 1.59 = 1/ 16

5 / 64 = .078125 = 5/ 64 = 1.98

6 / 64 = .09375 = 3/32 = 2.38 = 3 / 32

7 / 64 = .109375 = 7/ 64 = 2.78

8 / 64 = .125 = 1/8 = 3.18 = 1 / 8

9 / 64 = .140625 = 9/ 64 = 3.75

10/ 64 = .15625 = 5/32 = 3.97 = 5 / 32

11/ 64 = .171875 = 11/64 = 4.37

12/64 = .1875 = 3 /16 = 7.76 = 3 / 16

13/64 = .203125 = 13/64 = 5.16

14/64 = .21875 = 7/32 = 5.56 = 7 / 32

15/64 = .234375 = 15/64 = 5.95

16/64 = .25 = 1/4 = 6.35 = 1 / 4

17/64 = .265625 = 17/ 64 = 6.75

18/ 64 = .28125 = 9/32 = 7.14 = 9 / 32

19/64 = .296875 = 19/64 = 7.54

20/64 = .3125 = 5/16 = 7.94 = 5/16

21/64 = .328125 = 21/ 64 = 8.33

22/64 = .34375 = 11/32 = 8.73 = 11/32

23/64 = .359375 = 23/ 64 = 9.13

24/64 = .375 = 3/8 = 9.53 = 3/8

25/ 64 = .390625 = 25/ 64 = 9.92

26/64 = .40625 =13/32 = 10.32 = 13 / 32

27/64 = .421875 = 27/ 64 = 10.72

28/64 = .4375 = 7/16 = 11.11 = 7/ 16

29/64 = .453125 = 29/ 64 = 11.51

30/64 = .46875 = 15/32 = 11.91 = 15/32

31/64 = .484375 = 31/ 64 = 12.30

32/ 64 = .5 = 1/2 = 12.70 = 1 /2

33/64 = .515625 = 33/ 64 = 13.10

34/64 = .53125 = 17/ 32 = 13.49 =

35/64 = .546875 = 35/ 64 = 13.89

36/64 = .5625 = 9/16 = 14.29 = 9 / 16

37/64 = .578125 = 37/ 64 = 14.68

38/64 = .59375 = 19/32 = 15.08

39/ 64 = .609375 = 39/ 64 = 15.48

40/64 = .625 = 5 /8 = 15.88 = 5 / 8

41/64 = .640625 = 41/ 64 = 16.27

42/64 = .65625 = 21/32 = 16.67

43/64 = .671875 = 43/ 64 = 17.07

44/64 = .6875 = 11/16 = 17.46 = 11 / 16

45/64 = .703125 = 45/ 64 = 17.86

46/ 64 = .71875 = 23/32 = 18.26

47/64 = .734375 = 47/ 64 = 18.65

48/64 = .75 = 3 /4 = 19.05 = 3/ 4

49/64 = .765625 = 49/ 64 = 19.45

50/64 = .78125 = 25/32 = 19.84

51/64 = .796875 = 51/64 = 20.24

52/ 64 = .8125 = 13/16 = 20.64 = 13 / 16

53/ 64 = .828125 = 53/ 64 = 21.03

54/64 = .84375 = 27/32 = 21.43

55/64 = .859375 = 55/ 64 = 21.83

56/64 = .875 = 7/8 = 22.23 = 7 / 8

57/64 = .890625 = 57/ 64 = 22.62

58/64 = .90625 = 29/32 = 23.02

59/64 = .921875 = 59/ 64 = 23.42

60/ 64 = .9375 = 15/16 = 23.81 = 15 / 16

61/64 = .953125 = 61/ 64 = 24.21

62/64 = .96875 = 31/32 = 24.61

63/64 = .984375 = 63/ 64 = 25.00

64/64 = 1.0 = 1 = 25.40 = 1”

26.99 = 1-1 / 16

28.58 = 1-1 / 8

30.16 = 1-3 / 16

31.75 = 1-1/4
 
Very good info. I have & still do use 1/2" for 13mm, 3/4" for 19mm & 13/16" for 21mm for some fasteners & vice versa, they are a good fit.
 
I've got a similar chart on heavy paper hanging on the wall of my garage, with all the thousandth measurements of fractional sizes, and with full metric conversions in-between. Very handy.
 
harrisonm said:
I know most of us are at least somewhat familiar to the standard to metric tool conversions. For example, we all know that a 1/2" wrench is pretty much the same as a 13mm one. Every once in a while, I'll come across a nut or bolt head that is in between two standard sockets. Sometimes I wound up doing a trial and error to find the correct metric conversion. A while back I made up a table of inch to metric conversions in a spreadsheet. I thought I would post this table here. I checked it out very carefully, so I hope there are no errors. I hope it comes in handy for someone.


64th" Decimal" Reduced mm Socket
1 / 64 = .015625 = 1/ 64 = 0.40

2 / 64 = .03125 = 1/ 32 = 0.79

3 / 64 = .046875 = 3 / 64 = 1.19

4 / 64 = .0625 = 1/16 = 1.59 = 1/ 16

5 / 64 = .078125 = 5/ 64 = 1.98

6 / 64 = .09375 = 3/32 = 2.38 = 3 / 32

7 / 64 = .109375 = 7/ 64 = 2.78

8 / 64 = .125 = 1/8 = 3.18 = 1 / 8

9 / 64 = .140625 = 9/ 64 = 3.75

10/ 64 = .15625 = 5/32 = 3.97 = 5 / 32

11/ 64 = .171875 = 11/64 = 4.37

12/64 = .1875 = 3 /16 = 7.76 = 3 / 16

13/64 = .203125 = 13/64 = 5.16

14/64 = .21875 = 7/32 = 5.56 = 7 / 32

15/64 = .234375 = 15/64 = 5.95

16/64 = .25 = 1/4 = 6.35 = 1 / 4

17/64 = .265625 = 17/ 64 = 6.75

18/ 64 = .28125 = 9/32 = 7.14 = 9 / 32

19/64 = .296875 = 19/64 = 7.54

20/64 = .3125 = 5/16 = 7.94 = 5/16

21/64 = .328125 = 21/ 64 = 8.33

22/64 = .34375 = 11/32 = 8.73 = 11/32

23/64 = .359375 = 23/ 64 = 9.13

24/64 = .375 = 3/8 = 9.53 = 3/8

25/ 64 = .390625 = 25/ 64 = 9.92

26/64 = .40625 =13/32 = 10.32 = 13 / 32

27/64 = .421875 = 27/ 64 = 10.72

28/64 = .4375 = 7/16 = 11.11 = 7/ 16

29/64 = .453125 = 29/ 64 = 11.51

30/64 = .46875 = 15/32 = 11.91 = 15/32

31/64 = .484375 = 31/ 64 = 12.30

32/ 64 = .5 = 1/2 = 12.70 = 1 /2

33/64 = .515625 = 33/ 64 = 13.10

34/64 = .53125 = 17/ 32 = 13.49 =

35/64 = .546875 = 35/ 64 = 13.89

36/64 = .5625 = 9/16 = 14.29 = 9 / 16

37/64 = .578125 = 37/ 64 = 14.68

38/64 = .59375 = 19/32 = 15.08

39/ 64 = .609375 = 39/ 64 = 15.48

40/64 = .625 = 5 /8 = 15.88 = 5 / 8

41/64 = .640625 = 41/ 64 = 16.27

42/64 = .65625 = 21/32 = 16.67

43/64 = .671875 = 43/ 64 = 17.07

44/64 = .6875 = 11/16 = 17.46 = 11 / 16

45/64 = .703125 = 45/ 64 = 17.86

46/ 64 = .71875 = 23/32 = 18.26

47/64 = .734375 = 47/ 64 = 18.65

48/64 = .75 = 3 /4 = 19.05 = 3/ 4

49/64 = .765625 = 49/ 64 = 19.45

50/64 = .78125 = 25/32 = 19.84

51/64 = .796875 = 51/64 = 20.24

52/ 64 = .8125 = 13/16 = 20.64 = 13 / 16

53/ 64 = .828125 = 53/ 64 = 21.03

54/64 = .84375 = 27/32 = 21.43

55/64 = .859375 = 55/ 64 = 21.83

56/64 = .875 = 7/8 = 22.23 = 7 / 8

57/64 = .890625 = 57/ 64 = 22.62

58/64 = .90625 = 29/32 = 23.02

59/64 = .921875 = 59/ 64 = 23.42

60/ 64 = .9375 = 15/16 = 23.81 = 15 / 16

61/64 = .953125 = 61/ 64 = 24.21

62/64 = .96875 = 31/32 = 24.61

63/64 = .984375 = 63/ 64 = 25.00

64/64 = 1.0 = 1 = 25.40 = 1”

26.99 = 1-1 / 16

28.58 = 1-1 / 8

30.16 = 1-3 / 16

31.75 = 1-1/4
Click to expand...
In 1975, In Canada, it was a Federal prerequisite for graduation that we had to memorize this complete table. It made the multiplication tables a look like a walk in the park.
 
MrJLR said:
.03937
Click to expand...
YOU TOOK THE WORDS!!! Back in my parts days I worked for an outfit here in town, and we carried factory dist. for Fafnir ball bearings as well as Browning drive products, V belt sheaves, sprockets, and pillow blocks, etc. I carried a pocket calculator and used that figure many many times a day sometimes. .0394 is as accurate as you need.

CONVERTING DECIMALS if you cannot remember.

Fractions divide by the bottom, the denominator, so "figure it out"

.5 is 1/2
divide by two
.25 is 1/4

rinse repeat
.125 is 1/8

.0625 is 1/16

From then on I use the calculator and I used to have some memorized, like

5/16 is .3125

and 3/8 is .375

From there your trusty .0394 will get metric
 
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